South Korea's impeached President Yoon Suk Yeol will not attend the first formal hearing of the trial to determine if he is removed from office or reinstated because of concerns about his safety, Yonhap News reported citing his lawyer. The Constitutional Court hearing is scheduled for Tuesday. It will decide whether to uphold his impeachment or restore him to office. The Corruption Investigation Office for High-ranking Officials (CIO) is planning a new attempt to take Yoon into custody over a separate case relating to his failed attempt to impose martial law in early December. An arrest effort on January 3 failed after an hourslong standoff with security personnel at Yoon's fortified compound in central Seoul. “The officials in the Corruption Investigation Office and the police are trying to execute illegal and invalid arrest warrants through illegal methods, raising concerns about personal safety and mishaps,” lawyer Yoon Kab-keun was quoted as saying. "In order for the president to appear for the trial, the issue of personal safety and security must be resolved." Separately, investigators seeking to question Yoon on insurrection charges linked to his ill-fated martial law declaration are preparing another arrest attempt. The president's move to impose martial law plunged South Korea into its biggest political crisis in decades and hit growth expectations for Asia's fourth largest economy. Yoon's legal team say his guards remain on "high alert". Yoon would become the first sitting South Korean president to be arrested if investigators are able to detain him. If convicted, he faces prison or even the death penalty. A team of CIO investigators and police are planning for the next attempt, which they said could be their last. The CIO said anyone obstructing their attempt could be detained themselves and police reportedly held a meeting of top commanders on Friday to plan for the renewed effort. Former presidential guard security chief Park Chong-jun — who resigned on Friday and was automatically replaced by a more hardline Yoon loyalist — told reporters there must be no bloodshed in any second arrest attempt. The National Office of Investigation, a police unit, sent a note to high-ranking police officials in Seoul requesting they prepare to mobilise 1,000 investigators for the fresh attempt, the news agency reported. Rival protesters for and against Yoon have gathered almost daily in the South Korean capital since the crisis unfolded. As the crisis goes on Yoon's ruling party has seen a bump in approval ratings. A new Gallup survey published Friday showed the People Power Party's approval rating had risen to 34% from 24% three weeks ago.